As is well known and documented, cancer cells generally contain on their external surface specific neo-antigens which are foreign to the host body. Nevertheless, for reasons which are not entirely clear, the immune system fails to develop an effective immune reaction against the tumor cells. Attempts have been made to immunize cancer patients with preparations that will stimulate their immune systems to develop a reaction against the neo-antigens with the hope that such an immune reaction will destroy the residing cancer.
U.S. Pat. No. 4,931,275 discloses anti-tumor vaccines which contain as active ingredient tumor cells which have been treated to augment their immunogenic properties, their plasma membranes or specific membrane proteins obtained from these cells or membranes. The treatment which augments their immunogenicity in accordance with this patent consists of either treatment with cholesteryl hemisuccinate which rigidifies the lipid layer of the plasma membrane or by the application of hydrostatic pressure up to about 1500 atm, or a combination of the two treatments.